Control



June 13, 1944. s.- KNAAK CONTROL Filed July 16, 1942 I5 Sheets-Sheet 1INVENTOR. ORGE ffA/flfi/r.

ATTORNEY llllllllllllllllllll 4 Juhe 13, 1944. G, KNMK 2,351,216

CONTROL Filed July 16, 1942 3 Sheets-Sheet'Z I I 1N\/ENTOR.' GEORGE/Y190A.

ATTORNEY. w

G. KNAAK June 13, 1944.

CONTROL Filed July 16, 1942 3 Sheets-Sheet 3 I III,

Patented June 13, 1944 UNITED. STATES PATENT OFFICE v CONTROL GeorgeKnaak, Milwaukee, Wis. Application July s, 1942, Serial No. 451,101

16 Claims. (01. zoo-81.5)

This invention relates to a control device for regulating the operationof a refrigerating system, and more particularly to a thermostaticallycontrolled electric switch mechanism for controlling the starting andstopping of the electric motor employed in such a system to drive thecompressor thereof. 1

One of the objects of the present invention is to provide a controldevice of this character which facilitates the making of operatingtemperature changes frequently and easily. J

Broadly speaking, this object .of the invention is accomplished bycombining with the operating mechanism of the switch two sets ofbellows, lever, and spring mechanisms, bothcontrolled by the pressure onthe low or evaporating side of the refrigerating system, butindependently adjustable so that a difference between start and stop canbe adjusted to cover the entire range. I

Another and important object of the invention is to prevent starting ofthe system under adverse condensing pressures. By preventing startingagainst excessive head pressures,.a large factor in the cause of motortrouble is eliminated.

This latter object is accomplished in general by organizing with thecontrol a third bellows subject to the control of the pressure on thecondensing or high pressure side of the refrigerat-v ing system andexercising a dominant or master control in the device when theheadpressure is excessive. When the high pressure bellows is energized byvirtue of the existenceo'f excessivehea d pressure, operation of thevequipment cannot be resumed until thisv head pressure recedes to; apredetermined degree, a degree selected, .of course, with regard to thecapacity of the motor.

Another object of the. invention'is to provide'a controlling device ofthis character and having the advantages and capacities and which'isfsim-I ple and durable aswell as compact in construe-1 tion; reliableand efficient in operation and easy 1 and comparativelyv inexpensiveftolmanufacture and maintain. f I l Otherobjects and 'advantages'fresideino'ertain novel features of the construction, arrange-. ment, andcombination of parts, which will be hereinafter more fully describedfandparticularly pointed out in the appended claims, reference being had tothe accompanying drawings forme ing a part ofthis specification, aridinfiwhicht Figure 1 is a view in side elevationof a control deviceembodying the present invention, the cover plate of the housing of thedevice: being removed for the sake of illustration and the switch beingshown in'open pos'ition under the control of the cut-out bellowsresponsive to low side regulation;

Figure 2 is a view similar to Figure l but illus taken on line 4--4 ofFigure 2 and looking in the direction of the arrows;

Figure 5 is a view in transverse vertical cross section taken on line 55of Figure 2 and looking'in the direction of the arrows; 1

Figure 6 is a view in longitudinal vertical crosssection taken on line6-45 of Figure 4 and looking inthe direction of the arrows;

Figure '7 is a detail view in top plan illustrating the bellows-actuatedlevers employed to open and close the switch in response to lowside'regulation;

Figure 8 is a view thereof in side elevation;

Figure 9 is a detail view in front elevation of the lever employed forcontrolling the switch from the high pressure side of the system;

Figure 10 is a view in side elevation of the lever illustrated in Figure9; a

Figure 11 is a detailed view in front elevation of-the electric switchemployed for controlling the operation of'the motor;

Figure 12 is a view thereof in end elevation;

Figure 13 is a-detail view in top plan of the housing for the cut-in andcut-out bellows;

Figure 14 is a view thereof in longitudinal vertical cross section takenon line l4'l4 of Figure13;

Figure 15 is a fragmentary detail view in top plan showing the manuallyadjustable knob for the cut-out thermostat spring; and

Figure 16 is a view in vertical cross section taken on line |6l6 ofFigure 15.

Referring to the drawings, and more. particularly to Figures 1 to 6,inclusive, it will be seen that a control device embodying the presentinvention includes a suitable housing, designated generally at I, andpreferably constructed of sheet metal. The housing is in the form of arectangular box-like structure, and preferably has a removable cover 2.I p

Within the housing I is an electric switch, designated as a whole at S.The switch S is constituted to'provide a single pole, single throwswitch wherein snap action is provided by means of a permanent magnet.To'this end the switch carrier I l.

S comprises a panel 3 of insulatin material,

which is carried by a sheet metal bracket 4 fastened by screw 5 to oneof the walls of the housing. A fixed switch contact 6 is mounted on theinsulating panel 3 and may be carried by a portion of a binding post 1equipped with a binding screw 8 to facilitate the attachment of a leador wire (not shown) thereto. The fixed contact 6 is connected to oneside of the electric motor (not shown). but usually employed to drivethe compressorof a refrigerating machine. Cooperable with the fixedcontact 6 is a movable contact button 9. This contact button 9 may beriveted or otherwise suitably attached to ablade spring in (see Figures11 and 12) which is in turn fastened at one end to a pivoted contactcarrier II. The contact carrier II is provided with a circular openingthrough which the contact button 9 is projected under the influence ofthe inherent elasticity or bias of the blade spring [0. The lower end ofthe contact carrier [1' is fixed to and carried by a rocker arm l2preferably of insulating materialsuch as suitable laminated plasticcomposition. The hub of this rocker arm is pivotally supported on apivot bolt 13. The bolt I 3 extends through and is supported on abearing opening provided therefor in an extension 3 of the insulatingpanel 3 and the parts are held assembled by a nut l4 threaded on thebolt and coacting with the insulating panel. A flexible wire I5 isprovided and is connected at one end, as at 1'6, tothecontact Theopposite end of this wire I5 is connected to a binding post l1 fastenedto the insulatin panel by a screw l8 and equipped with a binding'screw19 to facilitate its connection 'to the opposite -side of the motorcircuit from thatto which the binding post 1 is connected. A retractilecoil spring 20 has one end attached tothejcontact carrier/ll and has itsopposite end fixed to thepanel 3, the spring 20 beingtensioned to biasthe switch S to closed position.

Combined with the" fixed contact 6 of the switch S is a permanent magnet2 l', the magnet 21 being'shown U-shaped or of horse-shoe form,

and having its legs straddling the fixed contact 6. The magnetic fieldof the magnet 2| so influences the contact carrier II, and the movablecontact 9, as to cause the switch S to open and close with a snapaction, thereby'minimizing arcing.

The opening and closing of the switch S is under thecontrol'of threebellows, designated generallyfat 31,532,, and B3. The bellows B1 and B2are in turnj controlled bythe' pressure on the low or evaporating sideof the refrigerating system. The bellows B3 is subject to the control ofthe pressure on the condensingor high pressure side of the refrigeratingsystem.

The controlling action of these bellows B1, B2, and B3 is' exerted onthe switch S through, a

special system' of lever and springs, which will sequently; both; thebellows B1;and B2 are Sub-r jected to the same pressure.

side of the refrigerating system; N The bellows housing 22 is preferablypositioned I below the bottom of the main housing I and is 1 fastenedthereto by screws 22 which also serve to secure supporting feet 21 tothe one side of the bellows housing 7 2 2.

The bellows B1 and B2 are operatively inter related with the operatingmechanism for the switch S through a novel and special system of levermechanism which will presently be described.

V This special type of lever mechanism is so combined with the bellowsand with the operating mechanism for the switch S that the bel, lows B1functions as a cut-out control in that when it exerts a controllingfunction on the switch S, it serves to shift the same to open position.The bellows B2 on the other hand is so combined with the operatingmechanism for the switch S that when it exerts a controlling functionthereover, it serves as a cut-in control, that is it functions to shiftthe switch S. to closed position". 1

. I The device, with only its bellows B1 and'Bz,

and with the. special type of lever and spring mechanism operativelyinterrelating with the switch S, is possessed of a capacity to exercisea very useful and advantageous purpose. Its function is enhanced byorganizing therewith the bellows Baresponsiveto the control of thepres-.

interrelating the bellows Bi and B2, with the operating mechanism forthe switch S, will now bedescribed.

The pointed or driving projections 28and 28' of the bellows B1 and B2extend up through openings provided therefor in the bottom wall of themain housing I. Supported on the fioor of the housing I and immediatelyover thejlbellows B1 and B2 is a bracket 30 constructed ofashe'et metalstamping of suitable gauge and servin'g'to support transverselyextending fulcrum pins'3l and 32. Thesefulcrum pins have the cross sec?7 tion shown in Figure 6 so as to presentdown wardly facing knife edgesdesigned to engage, suitable cooperative formations onthe upper surfacesof intermediate portions of the bellows levers 33 and 34 (see Figure 6).The under surfaces of these levers 33 and 34 at points spaced lengthwisethereof from the fulcrum pins 3| and 32, have socketed formations whichare in 00- operative engagement with the pointed. projections"28 and 28'of the bellows B1 and B2 (see Figures 5. and 6)..

Opposing the action of the bellows B1 and B2, on the levers 33 and 34areicoil springs 35 and 36, the, spring 35 being connected to thebellows lever 33 and the spring 36 to the bellows lever 34. The tensionof the springs 35 and 36 is independently variable or adjustable todetermine the range of operation of the control. 'The. structure bywhich the tension of springs 35 and 36 is varied oradju'sted will behereinafter more fully described. r

By having the cut-in and cut-out adjustments independent one from theother, a difference between start and stop can be adjusted to cover theentire range. Furthermore, since the adjustments ma be made on anoutside of the casing, operating temperature changes may be frequentlyand easilym'ade.

The manner in which'the levers 33 and 34 are operatively interconnectedwith the switch S will now be described; I I

The bellows lever 33 is provided with an arm or portion 31whichisicooperable with the inner end of a pin 38 carried by one arm ofthe rocker |2, so that when the lever 33 is'rotated in a;counter-clockwise direction, as viewed in Figure 1, its portion 31'pressesupwardly'on the inner end of the pin 38fto swing the rocker l2 ina clockwise direction and consequently cause the contact carrier I tocorrespondingly rota'te,thereby opening the switch or bring it to theposition shown in Figure 1. When this action occurs, the pressure in thelow side of the system has been reduced so that the spring 35 overcomesthe action of the bellows B1. As the evaporating coil of therefrigerating system warms up, the pressure in the coil, rises. Thiseffect a corresponding increase in the pressure in the bellows B1 andeventually the pressure therein reaches the point where it'overcomes theaction 'of the spring 35 so as to so move the lever 33to the positionshown in Figure 2, in which position the lever 33 will free theswitch Sand permit of its closure.

The closing of the switch S, when thehead or condensing pressure in thesystem is not excessive, is under the control of the cut-in bellows B2and its lever and'spring mechanism. s The bellows lever '34 of thebellows B2 has an upstanding lug 40 integral with its outer side edgeand'carrying an outwardly projection fixed pivot stud 4|. A switchcontrol lever, designated generally at 42, is pivotally supp rted on thepivot stud 4|. The switch control lever 42 has its body portionconstituted of sheet metal stamping of angular formation intransversevertical cross section. The vertical flange of the body portion of thelever 42.has a. bearing sleeve 43 fixed to and projecting from anopening provided therein. The pivot stud 4| extendsfthrough its bearingsleeve. A cotter pin 44 prevents 'endwise displacement of the sleeve orof the stud. Aspring finger 45 has one end riveted or otherwise suitablysecured to the horizontal flange of the body portion of the switch lever42, and its other end projects, beyond thehorizontal flange of the bodyportion of thelever and bears'against a pin 46 carried by the adjacentarm of the rocker of the switch S. Thevertical flange of the bodyportion of the switch lever hasa rearward projection 41 which overliesand is adapted to have engagement with a shortvertical pin 48 carried bya lateral extension 49 to the bellows lever 34. The extension 41 and pin48 provide a driving connection between the bellows lever 34 and theswitch control lever 42, and yet the switch control lever 42 mayberotated with respect to the bellows lever .34 in one direction for apurpose which will hereinafter more clearly appear. The spring finger45, while resilient, is sufiiciently stiff to hold the switch S openafter the switch has been moved to. open position byathe cut-out bellowsB1 and its lever and spring mechanism, since the spring finger isstiffer than the switch spring 20. The spring finger is not, however,sufliciently still to overcome the combined force of the switch spring20 and the permanent magnet 2| when the switch S is in closed positionand the contact carrier II and movable contact 9 are in the fieldofthemagnetzl.

The bellows B2 is hence eflfective to control'the closing of the switchS when the head 'or condensing pressure in the system is not excessive.It cannot, however, function to open the switch S since the control,which the bellows B2 exerts over switch S, is exerted through the springfln ger 45, which, as previously described, is not sufficiently stifl toovercome the combined force of the switch spring 20 and the permanentmagnet 2|. And during the phase of the operation that the bellows B2 iscontrolling the closing of the switch S, the spring finger 45 flexes toDrovide for the desired last.

The high pressure bellows B3 is enclosed in a bellows housing 50suitably fastened to one of the end walls of the main housing Thebellows housing 50 is provided with a fitting 5| to facilitate itsconnection with suitable thermostat or temperature element, such as thefamiliar capillary tube and bulb, with the bulb in clamped contact withthe condensing or high pressure side of the refrigerating system, so'thatthe pressure to which the bellows B3 is subject varies directly asthe pressure of the condensing or high pressure side of the system- Inmany instances the pressure of the refrigerant in the evaporating coilis utilized as the controlling medium'rather than the temperature. Thebellows B3 is'equipped with the usual pointed or driving projection 52which projects through an opening provided therefor in the adjacent endwall of the housing and also through an opening provided in a switchsupporting bracket, designated generally at 53 and suitably fixed to theinside of the end wall of the main housing adjacent the bellows B3. Alever, designated generally at 54, is supported for rocking movement ona pivot bolt 55 supported in suitable bearing lugs 56 which may beintegrally formed with the bracket 53. The lever 54 may beadvantageously constituted of a sheet metal stamping, and has a.plate-like arm 51 formed with a, depression or socket formation 58adapted to have suitable driving contact with the drivingprojection -52of the bellows B3. Integral with and projectingv angularly from theplate-like arm 51 are two lever arms, designated at 59 and 60,respectively. The lever arm 59 is connected to the lower end of aretractile coil spring 5|, the upper end of which is adjustablysupported on the top wall of the main housing The s ring 6| opposes theaction of the bellows B3. The arm 30 of the lever 54 is provided with alaterally projecting pin or roller 67. which overlies the verticalflange of the switch lever 42. When excessive condensing pressuresexist, the pressure on the bellows B3 is correspondingly in creased andthe projection 52 0f the bellows B3 rocks the lever- 54 in acounter-clockwise direction, as viewed in Figures 1; 2, 3, and 6. Thisswings the lever arm 8|! and itsroller or pin 62 down to the positionshown in Figure 3, in which position the roller 62 wipes against theupper edge of the vertical flange of the switch control lever 40,thereby rocking this lever 49 in a-counten clockwise direction andcausing its forward projection 43' to bear downwardly on the pin 46 soas to rock the rocker l2 and open theswitch S.

Aslong as theexcessive 'condensingpressures obtain, the switch S willremain open and thisindependently of'the action of the; bellows BiandB2. When the bellows Ba functions inthe manner described under theinfluence of'the excessive condensing pressures, it becomes the domi-'nant or master control and will maintain'the I switch S open. With theCOIlStlllCtlOn'shOWH the head pressure 'must recede about thirty-fivepoundstbefore the bellows B3 will'allow the, lever 54 to .rock backiromthe'position shown in Fig ure 3 to theposition shown in Figures -1 and2, and restore the control to the bellows B1 andBz. Various types'ofmean's may be employedfor adjusting the tension of the springs 35',36, and iii. The springs 36 and BI are shown as adjustable fromadjusting'screws 65 and 66, respectively. The heads of these screws aredisposed above the top of the casing and their threaded shanks extendvertically down and cooperate with nuts 61 and 68 permanently or fixedlyattached to the upper convolutions of their respective springs. Aplate-like key is combined with the nut 6'! and has sliding contactwiththe adjacent side wall of the'housing I to overcome any tendency of thenut or spring to turn. This expedient is not necessary with the spring6| since it is a lighter spring and can be manually held when its screwis adjusted. The spring also has'a nut H combined with the upper endthereof, the nut H having a plate-like key 12 in sliding contact withthe adjacent side wall of the housing. The screw 13 by which the spring35 is adjusted is threadedly engaged with the nut H and extends up abovethe top of the housing 1. A

collar '15 is fixed to the end of the screw projecting above the top ofthe main housing I and is formed with a series of radial slots 16extending outwardly through its periphery. A knob TI is placed above thecollar with its hub surrounding and in spaced relation to the upper endof the screw 13. The knob 11 has a depending driving lug 18 selectivelyengageable in the slots 16 and projecting down below the collar so as tobe cooperable with a stop lug I9 projecting up from the main housing. Aninternally threaded sleeve screw.80 is inserted in thehub of the knob TIand is threaded on the upper end of the adjusting screw 16 above theknob. The upper end of the sleeve screw 80 is formed with a flange 8!!which has clamping engagement with the knob to hold it in position withits driving lug positioned in the selected slot of the collar." Such aconstruction allows the user of the device limited adjustment of thecut-out bellows, thereby'facilitating ire-- quent and easy changes inthe operating temperature.

Obviously the device is susceptible to either pressure or temperaturecontrol and is not limited to use with capillary tube and bulb. Any ofthe standard temperature elements, such' as those adapted for closedtank immersion or for sensitive control immersion, or sensitive controlfor closed bellows B1, as well as for 'thefchamber; containing thebellows B2. More specifically; the bellows B2, which controls thecut-in, might be made responsive to the temperature of the coil toinsure complete defrosting, whereas the cut-out bellows B1 might be madesubject or responsive to the temperature of the environment 'beingcooled or the pressure of the refrigerant in the evaporating coil; a Y

While I have shown and; described one construction in which theinvention may be advantageously embodied, it is to be understood thatthe construction shown hasbeen selectedmerely for the purpose ofillustration or example, and that various changes in the size, shape,and arrangement of the parts may be made'without departing from thespirit of the invention or the scope of-the subjoi-ned claims.

Iclaim: 2; f Y I 1. A control device for the compressor motor of arefrigerating system comprising-a single pole, single throw electricswitch equipped with a permanent magnet to provide for snap action, aspring for biasing the switch to closed position, cut-out and cut-inbellows responsive to the pressure on the low pressuresideof therefrigerating system, two sets of levers,one connecting the cut-outbellows to the switch and the other connecting the cut-in bellowsthereto, the latter lever set having a yieldableelement :thereinstronger than the switch spring but weaker than the combined force ofthe switchspringand the permanent magnet, spring meanscombinedwith eachset of levers to oppose the action of its bellows thereon, and anindependent adjustment for each spring means whereby difference betweenstart and stop. can .be. adjusted to cover the entire range.v

2. A control deviceforthecompressor motor of a refrigerating system; ,anelectric switch for controlling the operation of .the. motor, anoperator-'for said switch, cutout and cut-in bellows subject to the pressurevariations on the low side of the system, alever actuated by the cutoutbellows and interconnected ,with the switch operator to cause it to openthe, switch upon a predetermined fall in the pressure on the low side ofthe system, a second lever actuated by the cut-in bellows, and. a leafor blade spring carried by said secondlever and cooperable with saidoperator to control the closing of the switch upon a predetermined ;risein pressure on the low side of the system. H

'3. A control'device' for the compressor motor of a refrigerating systemcomprising ahousing, an electric switch: therein for controlling theoperation of the motor, means responsive to the pressure on the lowpressure side fof the system for opening and closing said switch andinclud% ing a cut-out bellows associated with the housing, a leverfulcrumed within the housing, actuated by the cut-out bellows andcontrolling the opening of the switch, a retractilefcoil spring havingone end connected 'to 'said'lever, a nut secured to'the opposite end ofsaid spring, a

screw interthreaded with the nut and supported on the housing forrotation but held against axial movement and having a portion projectingexteriorly of the housing, in combination with a knob fixed to'theprojecting portion of the screw, and cooperating means between the knoband the housing for'limiting the extent to which the.

knob may be turned; I V g 4. A control; device for the compressor motorof arefrigerating system comprising a housing,

eration of the motor, means responsive to the 4 pressure on thelowpressure side of the system for opening and closing said switch andincluding a cut-out bellows associated with the housing, a leverfulcrumed within the housing, actuated by the cut-out bellows andcontrolling the opening of the switch, a retractile coil spring havingone end connected, to said lever, a nut secured to the opposite end ofsaid spring, a screw interthreaded with the nut and supported on thehousing for rotation but held against axial movernent and having aportion projecting exteriorly of thejhousing, in combination with acollar fixed to the projecting portion of the screw and having .acircumferential series of radial-slots ex tending out through theperiphery thereof, a ,knob having a combined locating and stop lugselectively interfitted with said slots, means for securing the knob tothe screw with its lug interfitted in a selected slot, and a fixed stoplug on the housing cooperable with the lug on the knob for, limiting theextent to which the knob may be turned.

5. A control device for the compressor motor of a refrigerating systemcomprising an electric switch for controlling the operation of themotor, means responsive to the pressure on the low the .cut-in bellows,an adjustable spring combined with the lever and opposing the action ofthe bellows, a switch control lever pivotally supported on and having aone way driving con-' ,nection with said bellows lever, and a leverspring fixed to the switch control lever and engageable with the drivingpin of the rockable switch operator normally to control the closing ofthe switch under the influence of the cut-in bellows.

6. A control device for the compressor motor of a. refrigerating systemcomprising an electric switch for controlling the operation of themotor, means responsive to the pressure on the low pressure side of thesystem for opening and closing said switch and including a rockableswitch operator having a laterally projecting driving pin, a cut-inbellows, a bellows lever actuated by the cut-in bellows, an adjustablespring combined with the lever and opposing the action of the bellows, aswitch control lever pivotally supported on and having a one way drivingconnection with said bellows lever, a leaf spring fixed to the switchcontrol lever and engageable with the driving pin of the rockable switchoperator normally to control the closing of the switch under theinfluence of the cut-in bellows, a high pressure bellows responsive tocondensing pressures, a lever actuated by said high pressure bellows, anadjustable spring combined with said last named lever and opposing theaction of said high pressure bellows, said last named leverhaving an armprovided with a camming portion cooperable with the switch control leverto shift it relative to its bellows lever and bring it into engagementwith the driving pin of the switch operator to open the switch upon theoccurrence of excessive head pressures and hold it open until the headpressure recedes to a predetermined value.

7. A control device for the compressor motor of a refrigerating systemcomprising an electric switch for controlling the operation of themotor, pressure-responsive means operatively interconnected with theswitch to open it upon a predetermined drop in pressure but beingineffective to apply a force thereto to cause it to close, andpressure-responsive means operatively interconnected with the switch toprovide for its closing upon a predetermined rise in pressure but beingineffective to control the opening of the switch.

8. A control device for the compressor motor I of a refrigerating systemcomprising an electric switch for controlling the operation of themotor, an adjustable pressure-responsive means, a onewaymotiontransmission train between said means and, said switch efiective to openthe switch upon a predetermined drop in pressure but being ineffectiveto apply force to the switch upon a rise in pressure, an independentlyadjustable pressure-responsive means, and a motor transmission trainbetween said last mentioned pressure responsive means and said switchproviding for closing of said switch upon a predetermined rise.inpressure but being ineffective to control the opening of the switch.

9. A control device for the compressor motor of a refrigerating systemcomprising an electric switch for controlling the operation of themotor, a cut-out bellows and spring arrangement operatively;interconnected'with the switch and normally acting as the sole means tocontrol the opening of the same upon a predetermined drop in pressure,and a cut-in bellows and spring arrangement also operativelyinterconnected with the switch and acting to control the closing of theswitch upon a predetermined rise in pressure but being ineffective inrespect of the opening of the switch.

10. A control device for the compressor motor of a refrigerating systemcomprising an electric switch for controlling the operation of themotor, a. cut-out bellows combined with the switch to open the same upona predetermined drop in pressure but ineffective to close the same, acut-in bellows combined with the switch to provide for closing of thesame upon a predetermined rise in pressure but ineffective to controlthe opening of the switch, and separate and inde pendent adjustablemeans for individually regulating the action of each of said bellows.

11. A control device for the compressor motor of a refrigerating systemcomprising an electric switch for controlling the operation of themotor, means for biasing the switch to closed position, a cut-outbellows operatively interconnected with the switch to open the same upona predetermined drop in pressure but being inefiective to close thesame, a cut-in bellows combined with the switch to control the closingof the same under the influence of its biasing means upon apredetermined rise in pressure but being ineffective to control theopening of the switch, and a separate adjustment for each bellowswhereby independent regulation is had over the action of the two bellowsso that a difference between start and stop can be adjusted to cover theentire range.

12. A control device for the compressor motor of a refrigerating systemcomprising an electric switch for controlling the operation of themotor, cut-out and cut-in bellows responsive to the pressure on the lowside of the refrigerating system, two sets of levers, one set of leversoperatively connecting the cut-out bellows to the switch to cause theswitch to open upon a predetermined drop in pressure, but being inefiec-"tiv'e to close "the same, the other'set of levers operativelyconnecting the cut-in bellows to the "switch to provide foreclosing ofthe switchupon =a predetermined rise in pressure but being in---eeeenvem-comr01 the opening of the same,

j spring-meanscombined with each set of levers to oppose the actionofits bellows thereon, and an independent adjustment for each springmeans whereby difference between start and stop 'can'beadjustedto-coverthe entire range.

: Q13. A control device for the compressor motor ota-refrigeratingsystem comprising an electric "switch for' controlling the operation ofthe motor, an operator for t-heswitch, a cut-out bellows I and'sprin'garrangement,-a lever actuated by the' cut-out-bellows and'springarrangement and -having a one-way driving connection with the switchoperator to cause'it to open the switch -upon 'a predetermined fall ofpressure but rende'ring' the lever ineffective to apply'force to theswitch upon a rise-in pressure, a cut-in bellows and spring arrangement,asecond lever actuated by the cut-in bellows and "spring arrangement,and a driving connection between said second lever and said switchoperator to provide for:

closing of the switch upon a predetermined rise in pressure butrendering the second lever ineffective' to control the opening of'theswitch, "and independent adjustments for said spring arrangements.

'14; -A--contro1 device for the compressor motor of a refrigeratingsystem comprising an electric switch-for controlling the operation ofthe motor, a rockable operator for the switch havinglaterally projectingdriving pins, a cut-out'b'ellows and-spring arrangement, a leveractuated by the cut-out bellows and spring arrangement and engageablewith one of said driving pins to eiiect opening ofthe-swit'oh upon apredetermined drop inpressure; acut-in bellows and springarrangefment,a'second lever actuated by the cut-in 1 bellows and springarrangement, and a yieldable connection betweenfsaid second-lever andthe other of said pins effective to control the clos- I ingof the switchupon a predetermined rise in 1- pressure but ineffectivein respect ofthe opening of the switch;

' 15. A-control device for the compressor motor of a refrigeratingsystem comprising an electric switch for controlling the operation ofthe m0- tor, an operator for the switch, a cut-out bellows and springarrangement, a'lever actuated by the cut-out bellows and springarrangement and having a one-way driving connection'with the switchoperator to causeit to open the switch upon a predetermined drop inpressure but inefie'ctive to cause the switch to close, a cut-inbellowsand spring arrangement, a second lever 'temand cooperable withsaid second lever to open said switch upon the occurrence of exces-'sive head pressure and to holdit open until the head pressure recedesto a predetermined value, said yieldable connection yielding uponfunctioning of said last mentioned means.

16. A control device for the pressure motor of a refrigerating systemcomprising an electric switch, means for opening and closing said switchincluding a first pressure responsive means, mo-

tion transmission means interconnecting said first pressure responsivemeans and said switch and effective to openthe switch in response to apredetermined fall in pressure but inefiective I to move the switch upona rise in pressure, a second pressure responsive means, and a secondmotion, transmission meansinterconnecting said second pressureresponsive means and said switch and" effective to close the switch upona predetermined rise in pressure," but inefiective to open" the switchupon a fall in-pressure, and means establishing fiuid'pressurecommunication between said first and second pressure responsive means.-a a c GEORGE KNAAK.

